基于ggplot在R中绘制分面多色垂直线展示各类型耗时的技术问询

Hey there! Let's fix this up so you get that Excel-style vertical line plot you're aiming for. The main hurdles right now are your wide-format data (ggplot2 works best with long/tidy data) and using the right geom to create those clean vertical lines instead of full bars.

Step 1: Load Required Packages #

First, make sure you have the tidyverse package installed (it includes ggplot2 for plotting and tidyr for reshaping data):

library(tidyverse)

Step 2: Define Your Dataset #

Here's your dataset as provided (formatted for readability):

df <- data.frame(
  type = c("X", "Y", "Z"),
  A_to_B = c(20, 56, 57),
  B_to_C = c(10, 35, 50),
  C_to_D = c(53, 20, 58)
)

Step 3: Reshape Data to Long Format #

We need to convert your wide data into long format so ggplot can easily map segments to positions. We'll also add an x column to assign numerical positions to each road segment (this helps place our vertical lines correctly):

df_long <- df %>%
  pivot_longer(
    cols = -type, 
    names_to = "segment", 
    values_to = "time"
  ) %>%
  mutate(
    x = case_when(
      segment == "A_to_B" ~ 1,
      segment == "B_to_C" ~ 2,
      segment == "C_to_D" ~ 3
    )
  )

Step 4: Create the Vertical Line Plot #

We have two options depending on exactly what you mean by "vertical lines at segment connections":

Option 1: Vertical Lines from X-Axis to Segment Time (Excel-Style)

This creates vertical lines starting at the x-axis (y=0) and extending up to each segment's time (like a bar chart but just the line, no fill):

ggplot(df_long, aes(x = x, y = time)) +
  # Draw vertical lines from y=0 to the segment time
  geom_segment(aes(xend = x, yend = 0), color = "steelblue", size = 1.2) +
  # Optional: Add points at the top of each line for clarity
  geom_point(color = "darkblue", size = 3) +
  # Split into facets by type
  facet_wrap(~type) +
  # Label x-axis with segment names instead of numbers
  scale_x_continuous(breaks = c(1, 2, 3), labels = c("A→B", "B→C", "C→D")) +
  # Add labels and title
  labs(
    x = "Road Segment",
    y = "Time (Units)",
    title = "Road Segment Time by Type"
  ) +
  # Clean up the theme
  theme_minimal()

Option 2: Only Vertical Connecting Lines Between Segments

If you want only the vertical lines connecting consecutive segments (no lines from the x-axis, just the links between segment times), we first calculate the previous segment's time and the midpoint between segments, then draw those vertical connections:

# Prepare data to get previous segment times and midpoints
df_connected <- df_long %>%
  group_by(type) %>%
  mutate(
    prev_time = lag(time),  # Get time of the previous segment
    mid_x = x - 0.5         # Calculate midpoint between current and previous segment
  ) %>%
  drop_na()  # Remove the first segment (no previous segment to connect to)

# Plot with only connecting vertical lines
ggplot(df_long, aes(x = x, y = time)) +
  # Show the segment time points
  geom_point(color = "darkblue", size = 3) +
  # Draw vertical connecting lines between segments
  geom_segment(
    data = df_connected,
    aes(x = mid_x, xend = mid_x, y = prev_time, yend = time),
    color = "steelblue",
    size = 1.2
  ) +
  facet_wrap(~type) +
  scale_x_continuous(breaks = c(1, 2, 3), labels = c("A→B", "B→C", "C→D")) +
  labs(
    x = "Road Segment",
    y = "Time (Units)",
    title = "Road Segment Time Connections by Type"
  ) +
  theme_minimal()

Explanation #

• Option 1 mimics Excel's standard vertical line chart, where each segment's time is represented by a vertical line from the axis.
• Option 2 focuses only on the connections between segments, which matches your description of "retaining only the vertical lines at the connections of each segment's time, not full bars".

内容的提问来源于stack exchange，提问作者Harshal Gajare